Sixth year

In her sixth year, she and Katie went on a weekend trip to Hogsmeade, and they stopped off for a drink in the Three Broomsticks Inn. Katie excused herself and went to the lavatory whilst Leanne sat alone in the pub. After some time she was spotted by Harry Potter sitting tapping her glass anxiously awaiting Katie's return. Finally, when she and Katie were returning to Hogwarts School of Witchcraft and Wizardry after their visit to Hogsmeade, she and Katie got in an argument over a package that Katie had been given to take to the castle, Leanne did not want Katie to take it, as its origins were unknown. The argument caused the girls to fight over the package and Katie to accidentally touch the cursed opal necklace that was given to her by Madam Rosmerta, who was under the Imperius Curse at the time, when the package's wrapping tore.

A shocked Leanne watches as her friend is cursed

Leanne was very distraught when Katie was put under the curse, trying to pull her down from the sky in which she floated above from and was seen crying. Harry, Ron and Hermione got to the scene and, with the help of Rubeus Hagrid, they got back to Hogwarts with Katie. When they got back inside the castle, Leanne broke down crying when telling Professor McGonagall what happened and was sent to Madam Pomfrey for calming down. After Katie has been healed and returned to Hogwarts, Leanne was present with her when Katie told Harry she did not know who gave her the package.

Seventh year

"Well, it’s not really like Hogwarts any more,"

—Neville Longbottom speaking of the school under the reign of Snape[src]

In the book, it is possible that she was a Gryffindor in Katie Bell's year, since Katie's line about Leanne having "just [been] telling [her] about McLaggen and the last match" can be read as to mean Leanne was one of Katie's seventh-year friends in the Gryffindor Tower, in that scene.

In LEGO Harry Potter: Years 5-7, Katie Bell's cursing is omitted and due to this, Leanne is absent from all the consoles versions of the game. However, Leanne is playable in the portable versions including the Nintendo DS and 3DS.